The present invention relates to a solenoid construction, and in particular, to a magnetic latching solenoid.
Magnetically latched solenoid structures are well-known in the art, and have utilized various permanent magnet materials for latching purposes, i.e. wherein a magnet acts to retain an independently operable solenoid plunger adapted for linear motion of a plunger operated push and/or pull actuating rod for motivating electrical switchgear towards open and/or closed circuit position. Prior art devices have shown placement of a permanent magnet circuit inside the solenoid""s magnetic circuit, and energizing the solenoid coil to cancel out the field of the permanent magnet, or to over power the magnetic field to affect motion. This materially affects the action of the operating components towards movement and latching activity.
It is an object of the present invention to provide a magnetic latching solenoid design, which improves upon the prior art by locating the latching permanent magnet(s) assemblies externally of the solenoid operating mechanism. This novel design approach outperforms the prior art in actuation speed and magnetic efficiency. The basic design concept is preferably used in connection with bi-directional operated latching solenoids. Certain aspects of the magnetic latching concept disclosed herein have application in both single and dual directional solenoid structures.
It is another object of the invention to provide a magnetically, operated actuator device, utilizing a permanent magnet latching assembly incorporating high-energy, permanent magnets of rare earth or other relatively fragile permanent magnet materials, and to provide a mechanical structure that protects such materials from damaging impact when subjected to motion of a solenoid plunger. The present concept may also use ceramic or Alnico magnets where their magnetic parameters permit.
Further, it is an object of the invention to provide a common pole piece in the center of the solenoid assembly. This allows the two axially spaced solenoid portions to operate magnetically independently, unlike conventional dual action solenoids, which suffer from magnetic leakage around opposite ends of the unit. Further, the present concept provides for the oppositely disposed latching members to operate independently from one another and from their respective solenoid construction.
Still another object of the invention is to meet industry requirements for circuit breakers controlled by the present dual-action solenoid, which is: Trip-Close-Trip, all taking place on stored energy. The disclosed design can accomplish this function at a low energy level, thus increasing storage cost efficiency.
It will be apparent upon reading the following description of the preferred embodiment that the invention provides, in its bi-directional mode, three movable structures assembled in one housing, one of which structures has linkage to the work load. The magnetic latching structures are magnetically independent of the solenoid structures, and each of the solenoids are magnetically independent of the other solenoid.